Transcript Cutaneous mycosis

Microbiology
Faculty of medicine
Islamic university-Gaza
Chapter 48
Cutaneous mycoses
Prepared by:
Mohammad Yousef Al-Najjar
Presented to:
Dr.Abdelraouf El-manama
Divisions of medical mycoses :
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•
•
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1-cutaneous
2-subcutaneous
3-systemic
4-opportunistic
Cutaneous mycoses
Dermatophytoses:
•Dermatophytoses are caused by fungi (dermatophytes)
that infect only superficial keratinized structures (skin,hair
& nails ) not deeper tissues.
•Classification of dermatophytes:
1-epidermophyton
2-trichophyton
3-microsporum
•They are spread from infected persons by direct contact.
•Microsporum is also spread from animals such as dogs
and cats.
•This indicate that to prevent reinfection ,the animal must
be treated also.
Dermatophytoses (cont.)
• Dermatophytoses (tinea,ringworm) are
chronic infections often located in the
worm, humid areas of the body, eg,
athlete’s foot and jock itch.
• Typical ringworm lesions have an inflamed
circular border containing papules and
vesicles surrounding a clear area of
relatively normal skin.
• Broken hairs and thickened broken nails
are often seen
Dermatophytoses (cont.)
• Trichophyton tonsaruns is the most
common cause of outbreaks of tinea capitis
in the children and is the main cause of
endothrix (inside the hair) infections.
• Trichophyton rubrum is also a very common
cause of tinea capitis.
• Trichophyton schoenleinii is the cause of
favus, a form of tinea capits in which crusts
are seen on the scalp.
Dermatophytoses (cont.)
• In some infected persons , hypersensitivity
causes dermatophytid (“id”) reactions,
eg, visicles on the fingers.
• Id lesions are a response to circulating
fungal antigens ; the lesions don’t contain
hyphae.
• Paitents with tenia infections show positive
skin test with fungal extracts, eg,
trichophytin.
Dermatophytoses (cont.)
• Scraping of the skin and nail placed in 10% KOH
on aglass slide show hyphae under microscopy.
• Cultures on Sabouraud’s agar at room
temperature develop typical hyphea and conidia.
• Tenia capitis lesions caused by microsporum
species can be detecting by seeing fluorescence
when the lesions are exposed to ultraviolet light
from a Wood’s lamp.
• Treatment involves local antifungal creams
(undecylenic acid,miconazole, tolnaftate, etc) or
oral griseofulvin. Prevention centers on keeping
skin dry and cool.
Tinea versicolor
• Tinea versicolor (pityriasis versicolor), a superficial skin
infection of cosmetic importance only, is caused by
malassezia furfur.
• The lesions are usually noticed as hypopigmented areas,
especially on tanned skin in the summer.
• There may be sight scaling or itching, but usually the
infection is asymptomatic. It occurs more frequently in
hot, humid weather. The lesions contain both budding
yeast cells and hyphae.
• Diagnosis is usually made by observing this mixture in
KOH preparations of skin scrapings. Culture isn’t usually
done.
• The treatment of choice is topical miconazole, but the
lesions have a tendency to recur and a permenant cure
is difficult to achieve.
Tinea nigra
• Tinea nigra is an infection of the keratinized
layers of the skin. It appears as a brownish spot
caused by the melaninlike pigment in the
hyphae.
• The causative organism, cladosporium
werneckii, is found in the soil and transmitted
during injury.
• Diagnosis is made by microscopic examination
and culture of skin scrapings.
• The infection is treated with a topical keratolytic
agent, eg, salicylic acid.
Thank you